The drugs were offloaded from a US Coast Guard cutter earlier this week, following seizures off the coast of Central and South America.
The crew of the Coast Guard cutter, Waesche offloaded the cocaine in San Diego following seizures in international waters during April and May.
The drugs were discovered on vessels off the coast of Central and South America during operations in the area.
The 21 tonne haul will now be destroyed.
An additional eight tonnes of cocaine, with an estimated value of $214 million, was also unloaded in Miami on 13 June.
This is believed to be the largest drug haul ever bought into Miami in the last five years.
The US Coast Guard said the Eastern Pacific Ocean and the Caribbean Basin are well known drug routes which is why patrols in the area have been stepped up.
The Coast Guard is working with many other US agencies to combat the trafficking of illegal drugs.
These include the US Navy, Department of Justice, the Department of Homeland Security, the FBI and the Drug Enforcement Agency.
It is also liaising with allied and international partner agencies.
Officials said that so far this fiscal year, more than 58 tonnes of cocaines has been seized.
Commander of the 11th Coast Guard District, Rear Admiral Joseph Servidio told NBC 7 San Diego that the transnational criminal organisations behind the drug trade “spread violence and instability wherever they operate”.
“There are thousands of deaths in the U.S. each year from cocaine overdose, and the production, transportation, sale and use of cocaine exact a very heavy human and social price throughout the Western Hemisphere and beyond,” he said.
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